Beam registration in striped color tube



Dec. 11, 1962 w. P. BooTHRoYD 3,068,317

BEAM REGISTRATION IN SIRIPED coLoR TUBE original Filed April s, 1951 2Sheets-Sheet l .NNI

Dec. l, 3962 w. P. BooTHRoYD BEAM REGISTRATION IN STRIPED coLoR TUBI:original Filed April 5. 1951 2 Sheets-Sheet 2 nite States ice BEAMREGISTRATION 1N STREED COLOR TUBE Wilson P. Boothroyd, HuntingdonValley, Pa., assignor,

by mesne assignments, to Philco Corporation, Philadelphia, Pa., acorporation of Delaware Continuation of applicationSen No. 219,093, Apr.3,

1951. This application Apr. 15, 1960, Ser. No. 22,645

Claims. (Cl. 1785.4)

The present invention relates to cathode ray tube systems for use in thereconstitution of visible images from signals representative of videointelligence, the instant case being a continuation of mycopendinglapplication Serial No. 219,093,` filed April 3, 1951. More particularlyit relates to such systems for use in the reconstitution of coloredimages from signals representative of intelligence with respect to'aplurality of color components of a tele- Yi'sedscene.

One of the principal diiculties whichbeset communications receiversusing such scanning devices as cathode ray, tubes in the presentation oftheir received intelligence lies in the fact that it is extremelydifficult to perform the necessary scanning i-nV a sufficiently uniformand consistent manner. Although byno means confined thereto, the natureand magnitude of this problem isV particularly well illustrated by Atheoperational shortcomings of-v color television receivers. Consequently,the detailed discussion to follow will concern itself principally withsuch color television-receivers, always pointing out, as the explantionprogresses, the broader fields of applicability of the inventiveconcept. v

One particular system of color television which is presently arousingwidespread interest is the so-called dotsequential system. In such asystem, there is produced a signal which is successively, indicativeof-the red, 'green and blue colorrcontent of smallelements of the scenewhich is to be televised. For this purpose, there may, for example, beprovided three simultaneously scanning television cameras, each of whichviews the scene to be tele# vised and each of which is equipped with aprimary color filter, so that one camera produces a video output signalwhose amplitude varies in accordance with the green elements of thescene, while the other two cameras produce output signals respectivelyindicative of the red and blue scene elements. The amplitudes of thethree output signals are then successively sampled, usually at equallytime-spaced intervals, producing a series of pulses occuring at thesampling intervals, and having amplitudes corresponding tothe amplitudeof the respective one of the three sampled color signals, also at thesampling intervals. The rate at which each of the original color signalsis sampled is very high, being equal to 3.6 megacyclesin some .presentlyrealized arrangements. These output pulses are then applied to a filterwhich converts them into a sinusoidally varyingA 3.6 megacycle signal,superimposed on a more slowly varying, or average component. Thiscolorsignal, suitablyl combined with t-he necessary` blanking andsynchronizing impulses in eventually received and from it the televisedscene must be reconstituted.

As indicated, the composite picture signalproduced in theabove-described manner is representative of color information at threetime-spaced intervals during each cycle of the 3.6 megacycle component.`Furthermore, since the original three continuous color signals aresampled in a predetermined recurrent order, the composite signal willalso be representative of the three colors in the same order.

-The receiver is further provided with a cath-ode ray tube whosescreenvis formed of minute and closely adjacent elements emissive ofcolored light -in response to cathode ray tube electron beam impingementand care is taken that these elements be disposed in the path of eachelectron bea-m sweep traversal so that the beam successively traverseselements respectively emissive of light of the three primary colors inthe same order in which these are represented inthe composite picturesignal.

With the beam intensity controlled, as usual, by the receivedsignal, allthatremains to be done is to ensure Ithat the electron beam be incidentupon a screen elef ment emissive of light of one particular colorprecisely at the interval at which the picture signal is representativeof such color. 1 l' v Unfortunately this has proven to be extremelydifficult to achieve for the following reasons. i

Firstly the position of the beamat any time during a sweep traversal `ofthe screen is dependenty upon a complica-ted deflection system whosebea-1n control characteristic cannot in practice be made perfectlylinear. Asa result, the rate of -beam traversal will vary in the courseof-each sweep traversal and the consecutive beam positions atwhich thebeam intensity corresponds to color information will not be uniformlyspaced along each sweep path. Furthermore, this non-linearity may bedifferent for different sweep traversals and may even changefrom time totime due to aging of deflection system components and the like. 'Y 'iSuch uncontrollable sweep non-linearity is, of course, incompatible withthe only simple Iarrangement of screen elementsv which is achieved byspacing them equally along'the sweep vtrace of the beam, because itproduces a` non-uniform sweep traversal rate, so that, withequallyspaced elements, the beam will sometimes be'incident on a particularelement at the time when its intensity is proportional to informationofthe proper color, while at other times itV will be incident upon aparticular elementwhen its intensity is not indicative of any color, oreven of the wrong color. With 558 screen elements disposed along eachsweep trace, an error'of onlyvtwotenths kof one percent in the rate ofbeam deflection would result in a positional error of one full screenelement near the end of the sweep, so that the resultant color renditionwould be completely erroneous.

Toobtain accurate color rendition, the linearity would actually have toVdepart fromthe ideal by considerably less than two-tenths of onepercent.

The foregoing `discussion assumes that thescreen elements, are actuallyuniformly spaced along each sweep trace. ,In practice this would rarelybe the case, so that even perfect sweep linearity would not alwaysinsure properly timed -beam impingement. y

The task of compensating for errors arising from these twov sources isrendered even more ditlicult by reason of the fact that changes in thepath followed by the picture signal betweenthe transmitter and thereceiver frequently produce varying delay of consecutive vportions ofthe picture signal with the result that the rate of reception of ypicturerinforr'nation may be temporarilyaccelerated or retarded. Changesdue to this entirely uncontrollable cause can, of course, not beanticipated by adjustment of the receiver equipment. 4

It is, accordingly, a prime object of the invention to provide apparatuswhich cooperates with a-scanning type data presentation device to reducetime differences between interyals at which received intelligence isavailable and intervals when such intelligence can be presented by thedevice.

Itis another object of the invention to provide means cooper-ating witha cathode ray tube to determine differences between the actual time ofimpingement of the cathode ray tube electron beam upon predeterminedportions of the tube screen and Ithe intended timev of such 3,068,317 lY f `impingen'lent and to modify the beam sweep so as to reduce thisdifference.

It is still another object of the invention to provide a colortelevision receiver with means yadapted to sense actual impingement ofthe display tube beam upon a predetermined portion of the screen,further adapted to derive information respecting the desired time ofsuch impingement from the received picture signal -and still furtheradapted to control the sweep rate of the display tube beam to decerasedifferences between the actual Yand desired times of impingement. i

It is a still further object of the invention to provide means, in acolor television receiver, for controlling'the rate of sweep of thereceiver cathode ray tube beam so as to compensate for color distortionproduced by sweep non-linearity and other types of non-uniform operatingcharacteristics.

To achieve the foregoing objects, as well as others which will appear, Iprovide my receiver with means -for deriving a `signal indicative ofcathode ray tube beam mpingement upon `suchdiscrete segments of the beamsweep'path as are adapted to produce visual indications of pictureintelligence. I provide further means for producing a signal indicativeof the occurrence of discrete intervals `at which the picture signal isrepresentative of picture intelligence, and I provide still furthermeans responsive to relative changes between these signals to controlthe sweep rate of the beam so as to minimize such relative changes.

To this end, the receiver cathodeV ray tube is equipped ywith so-calledindexing elements, which may comprise elements incorporated in thescreen structure and disposed between consecutive groups of ythreedifferently colored light emissive screen elements. Such indexingelements produce an electrical pulse signal each time the beam tioned sothat a constant phase comparator output of the said given value producesno control action on the deilection system. When, due to any of thevarious causes hereinbefore enumerated, these two rates yare no longerthe same, the phase comparator output will change. This output isapplied lto the delection system as a correction signal with suchpolarity as to reduce the phase comparator output change to a minimum.

A system `of the type heretofore broadly outlined is by 1.10 meanslimited, in its applicability, to color television systems, but isuseful wherever signal intelligence is available for reproduction onlyat discrete intervals.

The detailed construction and oper-ation of apparatus embodying theinvention will be more readily understood from a consideration ofv thefollowing detailed description together with the accompanying drawingswherein:

FIGURE 1 shows that portion of a color television receiver whichincorporates an embodiment of my invention, together with suchconventional apparatus as is intimately related thereto;

FIGURE 2 is an enlarged plan view of a cathode ray tube screen which maybe used in the embodiment of the invention shown in FIGURE l, randFIGURE 3 shows another embodiment of my invent tion together with thesame conventional apparatus as is shown in FIGURE l. Y

lIllustrated in FIGURE l to which more particular V*reference may now behad, is a signalsource 10, which impinges on one of them, and thesepulses in turn pro- A vide the .requisite indication of beam impingementupon the picture constituting screen elements. Note that thetime'spacing between consecutive ones of these pulsesv depends upon bothlinearity of beam sweep and uniformity of screen element spacing.

As for the above-mentioned signal indicativerof the Y occurrence ofdiscrete intervals at -which the picture signal isrepresentative ofpicture intelligence, it is immaterial to the practice of my inventionjust how this signal is produced. However, the usual color televisionsystem provides for the transmission of a color synchronizing signalwhich is independent of picture intelligence and whose frequency isindicative of the actual rate of occurrence 4of the aforesaid intervals.This synchronizing signal may beseparated yfrom the remainder of thecomposite signal at the receiver and used Ito produce Va signal havingthe same lfrequency and phrase characteristics and whose purpose it is`to provide the desired yindication of the loccurrence of intelligencerepresentative signal intervals.

Further inl accordance with the invention, this signal derived Vfrom thesynchronizing signal and the signal derived'lfrom the indexing elementsof the tube are both supplied to `a phase comparator where they producean output potential which is indicative of the phase difference betweenthe two signals. This output potential is then utilized to vary thenormal rate of deflection of the beam across the screen of the cathoderay tube in such a manner as to maintain'a predetermined desired phasedifference between the two signals. The deflection system can beinitially adjusted so that the uncontrolled may comprise such componentsof a conventional television receiver `as antenna, tuner,radio-frequency ampliers, converter, intermediate-frequency amplifiers,and video detector.v The'sgn-al which emanatesr from source 10 is thenthe composite received picture signal reduced to its lowest or videoyfrequency range. This signal comprises the -aforedescribed rapidlyvarying color component superimposed upon a more slowly varying averagelbrightness component. These two components are, at intervals of onescanning line, obliterated by the conventional blanking pulse which cutsolf the cathode ray tube scanning beam-during retrace intervals.Pedestaled upon the Yleading half of each such blanking pulse is ahori-4zontal synchronizing pulse, as is usual'in both color andblack-and-white television receivers. Upon the trailing half` of eac-hblanking pulse there is found the aforedescribed color synchronizingsignal which, as has been indicated, consists of la small number of halfcycles of -a sine wave having the nominal frequency of the color signalcomponent and having a reference phase indicative of the times at whichthis color signal is representative of color intelligence. Thiscomposite video signal, or' at least such portions thereof |as `arerepresentative of picture intelligence, are supplied by way of aconventional video lamplifier 11 to the beam intensity control grid 12of receiverdisplay tube 13. The same composite video signal is alsosupplied to blanking pulse gating circuit 14, which is so constructed asto be transmissive of signals applied thereto only during the intervalswhen a blanking pulse is present. Numerous conventional arrangementswill operate to perform `this function, as, yfor example, a triodeamplifier tube Whose Vcon-trol grid electrode is normally biased so 'farnegatively as to maintain the tube cut f imposed on each one Yof theseblanking pulses. These rate of traversal of the beam across coloredlight emissive synchronizing :signals are now further directed intoseparate channels, this being l'accomplished by means ofhori- Y zontalsynchronizing pulse separator 15 and color. burst separator 16,respectively. separators 15 and 16 mayV take any one of .a number ofconventional forms. -For example .they Inlay comprise narrow band-passYfilters vre- Y Ys-pectively transmissive 'of the Vfundamental frequencycomponentsof. the horizontal synchronizing pulses and of the colorsynchronizing bursts. In a typical case, the horizontal synchronizingpulse separator 15 may consist o-f a narrow band-pass filtertransmissive of signals of the standard 15.75 kilocycle line scanningfrequency to the substantial exclusion of all other signals. Similarly,in the particular case under consideration, the color synchronizingburst separator 16 may consist of a filter transmissive of 3.5 megacyclecolor synchronizing signals, again to the substantial exclusion ofsignals of all other frequencies. The output of horizontal sync pulseseparator 15 is utilized to drive a conventional horizontal oscillator-in the usual manner. The horizontal oscillator 17 is arranged so as toproduce a saWtooth wave of voltage which is applied to the control gridelectrode 18 of horizontal output Itube 19, Where it operates .tocontrol the output of this tube 19 in the usual manner. The output of-tube 19'is then applied, by way of horizontal output transformer'20, tothe horizontal deflection coil 21 of cathode ray tube 13, to controldeflection of-its beam in the usual manner. The high voltage end of theprimary winding of transformer 20 is, as is usual, connected to aily-back type high voltage supply 20a, where the oscillation set up inthe winding by the collapse of the transformer voltage vduring beamretrace is utilized to produce second anode potential for tube 13.

It .is customary, in deecting circuits of the sort above described, toprovide a so-called damping tube, connected across the deiiecting coil,which functions to damp out oscilla-tions which would otherwise be setup4in the coil during the rapid return of the beam between successivehorizontal scans. Asis well known, such a tube may also be adjusted toimprove the linearity of the scanning. In the present arrangement,thereris provided `a triode 22, similarly vconnected `across thedeflection coil 21, but which, in laddition to performing theusualfunctions of the conventional damper tube j'aforementioned, alsoperforms a further function in I:enzcordance with the present invention,as will be pointed out hereinafter.

Vertical beam deflection, on the other hand, may be provided by entirelyconventional vertical deflection circuits 23 actuated by receivedsignals from source 10 and connected to vertical deflection coil 24.

The output signal produced by color synchronizing burst separator 16 issupplied to a conventional cohered oscillator 25 which may compri-se amultigrid vacuum tube 50 whose control grid electrode 51 is connected tothe burst separator 16. The other electrodes of tube 50 are suppliedwith the usual operating potentials and the cathode, 'anode and controlgrid electrode 51 are further interconnected in oscillatory circuitrelation by means of resonant circuit 52 whose inductance andcapacitance elements Iare selected with such relative values that theoscillator is normally operative to produce a -signal ofthe nominalfrequency of the color synchronizing bursts. Such a cohered oscillatoris illustrated in FIGURE 21.14, on page 593, of Microwave Receivers,which is Volume 23 of the Massachusetts Institute of TechnologyRadiation Laboratory Series, published 1948 by McGraw-Hill Book Co.,Inc., New York. As a result of being supplied with suchcolorsynchronizing bursts from burst separator 16, this oscillator isyactually operative to produce a continuous signal having the samefrequency and phase characteristics as the intermittently occurringcolor synchronizing bursts. Thus cohered oscillator 25 provides a signalwhich is indicative of the rate of occurrence of intelligencerepresentative portions of the received signal. This, it will berecalled, is one of the signals required for the operation of -mysystem, as hereinbefore briefly explained. It w-ill also kbe recalledthat the other signal needed for this purpose is one which providesinformation as to the times and rate of traversal of the cathode raytube electron beam across screen elements capable of producing visibleindications of this signal intelligence. In accordance with theinvention, this second signal is derived directly from cathode ray tube13. For this purpose the cathode ray tube is provided with iso-calledindexing means. A variety of such indexing means are known `and it willbe understood, therefore, that the one described here has been selectedonly for purposes of illustration, and that :any other equivalent meansmay be substituted'therefor without departing from the scope of myinventive concept. Breily, cathode ray tube 13, in addition to havingthe conventional elements such as electron emissive cathode 26,accelerating anode 27, horizent-al deflection coil 21 and verticaldeflection coil 24, is 4also provided with a screen structure 28arranged as shown in the enlarged fragmentary view of FIGURE 2, to.which reference may now be had. This screen structure will be seen tocomprise a plurality of groups of parallel vertical phosphor stripes 29,30 and 31 of very narrow transverse dimensions which are preferably soclosely juxtaposed that individual stripes cannot be resolved by the eyeof an observer at ordinary viewing dis tance. These phosphor stripes arecharacterized in that every third one, as for example every stripe`numbered 29, is emissive of light of one of the primary colors, such asred for example,l in response to electron beam impingementthereon, whilethe intermediate stripes 30 andf31 produce light of the other -twoprimary colors, say green and blue, respectively, in response to suchelectron beam impingement. The order of occurrence of red, blue andgreen light emissive stripe-s in the pathof the electron beam during itshorizontal sweep .across the screen is, of course, the same as the'order of occurrence of intervals at which the received signal islrepresentative of intelligence relating to these three primary colors.Suitable materials constituting the phosphor stripes 29, 3.0 and 31 arewellknown to tho-se skilled in the 'art and further details concerningthe same are believed to be unnecessary. In the present embodimentthesephosphor stripes areseento have been applied directlyto the gl-assface plate 32 of the cathode ray tube. However, it will. be understoodthat this need not be yand that,- instead, the entire screen structure28 may be formed' on a suitable light `transparent base which isindependent of the face plate 32 and may be spaced therefrom.

The screen structure 28 further comprises athin electron permeable layer33 which covers phosphorrstripes 29, 30 and 31 and which preferablyfurther constitutes a mirror for reflecting light generated by thephosphor stripes. In practice thelayer 33 may be a light'reflectingaluminum coating which is formed in well known manner.

Arranged over every third phosphor stripe, such as stripe 29, is anindexing stripe 314 consisting of a material, such as gold, having asecondary emission ratio substantially dilferent from that of thematerial of coating 33. Since the detailed representation of this entirescreen structure would obscure the important features of the ndexingarrangement, only the indexing stripes have been actually shown, andthese have been diagrammatically represented by vertical lines 34a. Fora more detailed discussion of the disposition and composition of screenstructures including indexing stripes, reference may be had to U.S.applications of David E. Sunstein, lSerial No.

547,621, filed November 18, 1955 and of Carlo V. Bocciarelli, Serial No.198,709, filed December 1, 1950, both assigned to the assignee of thepresent invention'. Second anode 35 which, as is usual, consists of aconductive coating applied to the inside of the cathode ray tube nearthe screen attracts secondary emission electrons emanating yfrom theseindexing stripes by virtue of the high positive potential appliedthereto from high voltage supply 20a. Thus, every time the electron beamsweeps across an indexing stripe during lits horizontal sweep traversalof the screen, the flow of secondary emission electron-s to second anode35 will momentarily increase and so will the current through indexoutput resistor 36 which is connected between the second anode and thetube screen. These momentary current increases indichative of intervalsdurtransformed into corresponding pulses b y RJC network 37,` 38 whoseoutput is, in turn, utilized to control a cohered oscillator 39. Thislatter may, in all respects, be identical to the cohered oscillator 25to which the output of burst separator 16'is supplied and, consequently,does not require separate description here. Sufliee it to mention`that'thiscohered oscillator prod-uces an output signal having the samefrequency and the same phase as the indexing pulses derived from thecathode ray tube screenl Cohered oscillator 39 thus constitutes thesource kof a signal which is indicative of intervals at which thecathode ray tube electron beam is incident upon colored light emissiveelements.

It, will be apparent, from a consideration of the foregoing description,that the amplitude of the indexing ,signaly produced by the index outputcircuit hereinbefore described will be somewhat dependent. upon theintensity of the electron beam which is, lin turn,V determined by signalinformation.v This contamination of the indexing pulses `by the receivedsignal may, in some cases, necessitate-more elaborate preeautionsrtomake sure that the cohered oscillator 39 is actuated only by theindexing pulses properrl Various means are available for reducing oreliminating the etfect of this contamination, as for example thosedescribed in U.S. Patent No. 2,644,855,

issued July 7, 1953 to William E. Brad-ley on an applica-` tion ledDecember 28, 1950 and assigned -to the assignee of the presentinvention. It is, of course, within my contemplation that suitable meansof this type be used whenever the indexing signal produced ashereinbefore described is excessively contaminated by the receivedsignal.

The output signal derived from cohered oscillator 215 and that producedby cohered oscillator 39 are now applied to thefinput circuits of aphase comparator v40 vvhichfrnayA lbe of any conventional type adaptedto produceV a unidirectional output potential Iproportional to the phasedifference between the signals supplied thereto. For example, this phasecomparator may comprise a pair or' diode vacuum tubes 53 and 54, whoseanodes are connected together by series lresistors 55 and 56 and by thesecondary winding of transformer 57. The cathodes of 'these same diodesare connected together through two serially connectedresistance-capacitance networks 58 and 59 and the junction of these R-Cnetworks is con nectedv tofa Vcentertap on the aforementioned Vsecondarywinding of transformer 57 through theV secondary winding of anothertransformer 60.. When the primary windings of these transformers 57 andare, as illustrated, connected to the cohered oscillators 39 and 2.5,respectively, so that the oscillatory output signals ofthe latter varedeveloped thereacross, then 'there will .be developed across the two R-Cnetworks 58 andS), a unidirectional potentialwhose magnitude varies inproportion to variationsin the phase difference betweenthe twooscillator output signals. Such avphase comparator is shownin FIGURE 1on page 1401 of volume 37 of Y Proceedings of the LRE, 1949. Thisunidirectional output potential produced by phase comparator 40 issupplied' to control grid 41 of damper triode 22 for the purpose ofcontrolling the latter in a manner here- Y inafteir explained. l

`Observe now that, soV long as the frequencies of 'the signalsA derivedfrom cohered oscillators 25 and 39 are tho same and so long as theirphase relationship remains constanLthe phase comparator output potentialwill re- Amain' constant. VMoreV particularly, a certain constantunidirectional potential will be produced b y phase comparator 40Whenever the rate of beam `sweep traversal 'across the screen of cathoderay ktube 13 is exactly the Vsame Zasthe rate of occurrence ofintelligence repre- In accordanceV sentative portions in the receivedsignal. with myinvention, the circuit parameters associated withhorizontal output tube 19 and damping tube/22 are so 8 adjusted thatwhen they grid 41 of damping triodeZZ'is supplied withy an output ofthephase comparator which is indicative of equality of sweep andintelligence occurrence rates, triode ZZ Will'be vcausedl tov conductuniformly throughout therentire sweep Vinterval with such intensity asto produce a current through horizontal deiiection .coil 21 which willsweep the beam across the tube face at a rate just sucient to maintainthis output potential constant. The phase comparator 4i) is furtheradjusted so that aphase delay of the signals derived from coheredoscillator 39 with respect to those produced by cohered oscillatorV 25,denoting a rate of beam sweep traversal which is too slow with respectto the rateV of intelligence occurrence will produce a change in theunidirectional output potential of the phase comparator in The. effectof this cooperative functioning of Y'phase Y comparator 40 and dampingtriode 22 is to insure the desired correspondence-between the rate ofoccurrence ofl intelligence 'representativeportions of the receivedsignal and the rate of beam Asweep ltraversal of cathode ray tube screenelements which are adapted to reprovduce this intelligence.

Instead-of using a two'windiug transformer such as thatddesignated byVreference numeral 20 in FIGURE l,

it'is Vsometimes preferredl to use an auto-transformer' betweenV theAhorizontal output tube of the horizontal deection system and thehorizontal deection coil of the cathode ray tube. Whenever that is thecase there will exist a direct current connection between the outputelectrode of this horizontal output tube and the deilection coil. Thismakes it inappropriate to use a damping triode -such astube 22 of FIGUREl forY a deflection coil current controlling element 4in accordance withthe invention, inasmuch as its control grid would not be exclusivelydeterminative of its rate of conduction. Instead, anode voltage changesbrought about byrconduction changes in the horizontal output tube wouldproduce an additional uncontrollable etectcn the deflection coilcurrent. In

such afcase, there Vmay `befsubstituted for the triode damping tubeyarrangement of FIGURE 1 a different circuit, suchA as, for example,that of FIGURE Y3 to which moredetailed reference may now be had.

n Note, first Vof all, that with the exception of the actual deflectioncircuit of the cathode ray tube, FIGURE 3 is substantially identicaltoFIGURE 1. That is, both embodiments have numerous identical componentsand these have, for ease of comparative identication, been designated bysimilar reference numerals. Furthermore, certain of the elements whichrwere shown by circuit diagrams in FIGURE 1 have Ybeen illustrated, forthe sake of simplicity, by block diagrarnsvin FIGURE 3.

j Thus, the system of FIGURE` 3, like that of FIG- URE 1, includes asignal source 10 at whose output there is available-the Vcompositereceived video signal together with its blanking pulses and horizontaland color synchronizing signals. This composite signal is again suppliedto thebeam intensity control gridj12 of cathode ray Vtube V13 by way ofvideoampliiier 11, while the blanking ,pulses alone actuate` gatingcircuit V14 thereby supplyingsynchronizing signals to horizontalsynchronizing pulse separator 15 and color synchronizing bursts toV thecontrol grid electrode 18 of horizontal output tube 19. The colorsynchronizing burst separator 16, on the other hand, feeds a coheredoscillator 25 which produces a continuous output signal having the samefrequency and phase characteristics as the color bursts.

Like that of FIGURE 1, cathode ray tube 13 includes the conventionalelements such as electron emissive cathode 26, accelerating anode 27,horizontal and vertical deflection coils respectively designated 21 and24, second anode 35 and a screen 28 including indexing stripesdiagrammatically represented by vertical lines 34a. The index signaloutput from this cathode ray tube is again derived across index outputresistor 36, formed into Vpulses by R-C network 37, 38 and utilized todrive cohered oscillator 39 which produces an output signal having thefrequency and phase characteristics of the index signals. The outputs ofcohered oscillators 25 and 39 are again supplied to the input circuitsof phase comparator 40. As for the deflection system proper, this latternow consists of a single winding auto-transformer 42. Across a portionof this auto-transformer there is connected the horizontal deflectioncoil 21 in parallel with a conventional diode damping tube 43, while aconventional high voltage supply 42a is energized from the high-voltageend of Winding 42. A conventional voltage boosting capacitor 44 is alsoprovided between the anode of damping diode 43 and the low voltage endof auto-transformer winding 42. It is across this voltage boostingcapacitor 44 that an auxiliary control triode 45 is connected forthepurposes of my invention. To the control grid electrode 46 of thisauxiliary triode 45, there is supplied the unidirectional outputpotential produced by phase comparator 4) in response to the signalssupplied thereto to cohered oscillators 25 and 39. While the arrangementof the deilecton system, with the `exception of the` provision ofauxiliary triode 45 looks somewhat like a conventional system of thistype,- it nevertheless diiers therefrom in that the circuit parametersassociated with the horizontal output tube 19 are so chosen as to renderdiode 43 conductive during the entire sweep interval rather than onlyduring parts thereof as was the practice in the prior art. In thisarrangement, the presence of auxiliary triode 45 has the effect ofcontrolling the load on boosting capacitor 44 so as to adjust theeffective voltage across the damper diode 43 to provide the desired rateof change of current in the deflection coil 2l. Once again, the systemis so adjusted that, with proper correspondence between the rate of beamsweep traversal, as determined by the rate of change of deflectioncurrent in deilection coil 21, and the rate of intelligence occurrencein the received signal, there will be produced, by phase comparator 40,a` unidirectional control potential which will control the conductionthrough triode 45 so as to maintain the aforesaid desiredcorrespondence. Again the phase comparator will be s o arranged thatchanges in the relative rate of the beam sweep traversal and of tneintelligence occurrence will produce compensatory changes in theconduction of auxiliary triode 45 and therefore also in the rate ofcurrent Achange in deflection coil 21.

The preceding discussion has been limited to television receiver systemsusing electromagnetic deflection systems for their cathode ray tubes. Itwill be understood, however, that the applicability of my inventiveconcept is by no means limited thereto. Thus, for example, the'teachings of my invention may be applied with equal success to thedeilection control of electrostatic deflection systems or indeed of anyothers that may be conceived. Since numerous modications in this andother respects will occur to those skilled in the art without departingfrom my inventive concept, I desire the latter to be limited only by theappended claims.

I claim:

l. In combination: a source of an intelligence signal; a source of asecond signal synchronized with said intelligence signal and having aparameter indicative of the rate of change of intelligence in saidintelligence signal; a cathode ray tube including a source of anelectron beam, a beam intensity control electrode, a screen having aplurality of parallel strip-like regions of tluorescent material, and aplurality of strip-like indexing elements placed near spaced ones ofsaid tluorescent strips, each of said indexing elements being responsiveto beam impingement to produce an indexing signal indicative of suchimpingement; means for applying said intelligence signal to said beamintensity control electrode; means for deflecting said beam to cause itto scan said screen relatively slowly in a direction generally parallelto said uorescent strips and to said indexing elements and relativelyrapidly in a direction generally transverse to said iluorescent stripsand to said indexing elements, said last-named means being responsive toa control signal to vary the rate of deflection of said beam in saiddirection transverse to said fluorescent strips and to said indexingelements; means for deriving from said indexing signal a Vsignal havinga parameter indicative of the rate of traversal of said indexingelements by said beam; a signal comparing circuit having a pair of inputcircuits and an output circuit, said input circuits being supplied withsaid last-named signal and with said second signal respectively and saidsignal comparing circuit being responsive to relative changes in saidparameters of said supplied signals to produce in said output circuit asignal indicative of saidrelative changes; and means for applying saidlastnamed signal to said deflection means as a control signal to alterthe rate of dellection of said beam by said means.

2. In combination: a source of a rst signal of varying amplitude whoseamplitude, at time-spaced intervals, is representative of signalintelligence; a source of a second signal synchronized with saidintelligence signal and having Ia frequency indicative of the rate ofoccurrence of said intervals; a cathode ray tube' including a source ofan electron beam, a beam intensity control electrode and a screencomprising Ia plurality of substantially parallel phosphor lines; meansfor applying said intelligence signal to 'said beam intensity controlelectrode; means Vfor dellecting said beam to cause it to scan saidscreen relatively slowly in a direction generally parallel to saidphosphor lines and relatively rapidly in a direction generallytransverse to said phosphor lines, said last-named means beingresponsive to a control signal to vary the rate of deflection of saidbeam in said direction transverse to said phosphor lines; meanscooperating with said screen structure and responsive to electron beamimpingement upon portions of said screen structure which are spaced bythe same intervals as said parallel phosphor lines to develop a thirdsignal whose frequency is indicative of the rate of traversal of saidphosphor lines by said beam; a phase comparing circuit supplied withsaid last-named signal and with said second signal and responsivethereto to produce .a signal indicative of variations in phase betweensaid two signals; and means for applying said produced signal to saiddeilecting means as a control signa-l to control the rate of deflectionof said beam to cause said beam to impinge said phosphor lines at timessubstantially corresponding to the intervals during which said firstsignal is representative of intelligence.

3. In combination: a source of an intelligence signal of varyingamplitude, the amplitude of said signal, at time-spaced intervals, beingrepresentative of information with respect to different colorcomponents, information -relative to different color componentsrecurring cyclically in a predetermined sequence; a source of a secondsignal synchronized with said intelligence signal and having a frequencyindicative of the rate of occurrence of said intervals; a cathode raytube including a source of an electron bea-m, a beam intensity controlelectrode, and a screen comprising a plurality of substantially parallelphosphor lines of diiferent color ernissivities correspondlingrespectively to the color components represented in beam to cause it toscan said Yscreen relatively slowlyV in a direction generally parallelto said phosphor lines and relatively rapidly in ya direction generallytransverse to said phosphor lines, said last-named means beingresponsive to a control signal to vary the rate of'deection of said beamin said direction transverse to said phosphor lines; means cooperatingwith said screen to produce a signal whose frequency is indicative ofthe rate of traversal of said phosphor lines by said beam; a phasecomparing circuit responsive to said last-named signal and to saidsecond signal to produce a signal indicative of variations in phasebetween said two last-named signals, and means for applying saidproduced signal to said detlecting means as a control signal to controlthe rate of deiiection of said beam to cause said beam to impinge eachof said phosphor lines at a time substantially corresponding to Vaninterval during which said intelligence signal is representatijzle ofcolor component information corresponding to the color emissivity ofsaid line.

4. In combination: a source of an intelligence signal of varyingamplitude, the amplitude of said signal being representative of red,green and blue color component information at time-spaced intervalsrecurring cyclically in a predetermined sequence; a source of .a secondsignal synchronized with said intelligence signal and having a frequencyindicative of the rate of occurrence of said intervals, a cathode raytube including a source of an electron beam, a beam intensity controlelectrode, a screen comprising a plurality of substantially parallelphosphor stripes of red, green and blue color emissivities, recurringcyclically across said screen in the same sequence as the colorinformation in saidv intelligence signal, `and a plurality of indexingstripes paralleling said phosphor stripes and disposed across saidscreen at intervals of three phosphor stripes; means for applying saidintelligence signal to said beam intensity control electrode;V means fordeflecting said beam to cause it to scan said screen relatively slowlyin a direction'generally parallel to said phosphor stripes and to saidindexing stripes and relatively rapidly in -a direction generallytransverse to said phosphor stripes and said indexing stripes, saiddetlecting means being responsive to a controlV signal to vary the rateof deection ofl saidrbeam in a direction transverse to said phosphorstripesand to said indexing stripes; means for deriving from saidindexing stripes a signal whose frequency is indicative of the rate oftraversal of said phosphor stripes'by said beam; a phase comparingcircuit supplied with said last-named signal and with said seco-ndsignal and responsive thereindexing elements being respo-nsive to beamimpingement to produce an indexing signal indicative of suchimpingement;means for applying'said intelligence signal to said beam intensitycontrol electrode; means for deflecting said beam to cause it to scansaid screen relatively slowly in a direction generally parallel to saidiluorescent strips `and to said indexing elements and relatively rapidlyin a direction generally transverse to said fluorescent strips and saidindexing elements, said last-named means being responsive to a controlsignal to vary the rate of deflection of said beam in a directiontransverse to said fluorescent strips and to said indexing elements;means for deriving from said indexing signal a signal having a frequencyindicative of the rate of traversal of said indexing elements by saidbeam; a phase comparator supplied with said last-named signal and withsaid produced continuous signal and responsive to said supplied signalsto develop a signal indicative of the relative phase variations of saidsupplied signals; land means for applyingrsaid developed signal to saiddeflecting means as a control signal to alter the rate of deflection ofsaid beam in said direction generally transverse to said liuorescentstrips` 6. In combination: a source of an intelligence signal; a sourceof a second, intermittently occurring signal synchonized with saidintelligence signal and indicative of Ythe rate of change ofintelligenceV in said intelligence sigl nal; meansV supplied with saidsecond signal and responsive thereto to produce a continuous signal insubstantial synchronism with said intermittent signal; a cathode raytube including a source of an electron beam, a beam intensity controlelectrode, a screen having a plurality of parallel Vstrip-like regionsof iluorescent material and a plurality of strip-like indexing elementsplaced near spaced to `to develop a control signal indicative ofvariations in t phase between said two supplied signals; and means forapplying said produced signal to said deflecting means as a controlsignal to control the r-ate of detiection of said beam to canse saidVbeam to impinge upon each of said phosphor stripes at a timesubstantially corresponding to an Iinterval during which saidintelligence signal is representative of'color component informationcorresponding to the color emissivity of said stripe.

5. In combination: al source of an intelligence signal; a source -of asecond, intermittently occuring signal synchronized with saidintelligence signal and having a frequency, during occurrence, which isindicative of the rate of change of intelligence in said intelligencesignal; means supplied with said second intermittent signal andresponsive thereto to produce a continuous signal in Subsubstantialsynchronism with said intermittent signal; a cathode ray tubeincluding'la source of l.an electron beam, a beam intensity controlelectrode, a screen having a plurality of parallel strip-like regions ofiluorescent material and a plurality of strip-like indexing elementsplaced near spaced ones of said uorescent strips, each of said ones ofsaid iluorescent strips, each of said indexing elements being responsiveto beam impingernent to produce an indexing signal indicative of saidimpingement; means for applying said intelligence signal to said beaminten-V sity control electrode; means for deflecting said beam to causeit to scan said screen relatively slowly in a direction generallyparallel to saidfluorescent strips and to said indexing elementsand'relatively rapidly in a direction generally transverse to saiduorescent strips and said indexing elements, said last-named means beingresponsive to a control signal to vary the rate of deflection of saidbeam in a direction transverse to said iluorescent strips and to saidindexing elements; means for deriving from said indexing signal a signalhaving a frequency indicative of the rate of traversal ofsaid indexingelements by said beam; a phase comparator supplied with said last-namedsignal and with said produced continuous signal and responsiverto saidsupplied signals to develop a signal indicative of the relative phasevariations of said supplied signals; andmeans for applying saiddeveloped signal to said deflecting means as a control signal to alterthe rate Vof deflection of said beam in said direction generallytransverse to said fluorescent strips.

7. In combination: a source of an intelligence signal; a source of asecond, intermittently occurring signal synchonized withsaid-intelligence signal and having aparameter indicative of the rate ofchange of intelligence in said intelligence signal; means supplied withsaid second signal and responsive thereto to produce a continuous signalin substantial synchronism with said intermittentV signal; a cathode raytube including arsource of an electron beam, a beam intensity Vcontrolelectrode, a screen having a plurality of parallel strip-like regions offluorescent material and aplurality of strip-like indexing elementsplaced near spaced ones of said fluorescent strips, each of saidindexing elements being-responsive to beam impingement tofproduce'anindexing signal indicative of said impingement', means for applying saidintelligence signal to said beam intensity control electrode; means fordeilecting said beam to cause it to scan said screen relatively slowlyin Va direction generally parallel to said uorescent strips kand to saidindexing elements and relatively rapidly in a direction generallytransverse to said uorescent strips and said indexing elements, saidlastnamed means being responsive to a control signal to vary the rate ofdeflection of said beam in a direction transverse to said fluorescentstrips and to said indexing elements; means for deriving from saidindexing signal a slgnal having a parameter indicative of the rate oftraversal of said indexing elements lby said beam; a signal comparingcircuit supplied with said last-named signal and with said producedcontinuous signal and responsive to said supplied signals to develop asignal indicative of relative changes in said parameters of saidsupplied signals; and means for applying said last-named signal to saiddeection means as a control signal to alter the rate of deection of saidbeam by said means.

8. In color television receiving apparatus for receiving waves includingcontrol signals and signals occupying respectively dierent regularlyrecurring phases of a transmitted cycle and representative respectivelyof different component `colors of the transmitted image, means forproducing an electron beam, a screen containing color phosphorsluminescent in different colors when energized under impact of theelectron beam, means for scanning the electron beam over the screen,said scanning means and said screen lbeing constructed so that dierentcolor phosphors are imping'ed upon'by the beam in regular order `ofrecurrence during each scanning line, and means responsiveto controlsignals in the received waves for con'- trolling the energization of thediierent color phosphors along each separate scanning line to make theirenergization accord with the dilerent phases of the color representativesignals. Y

Y 9. In color television receiving apparatus for receiving wavesincluding control signals and signals representative respectively ofdifferent componentY colors of the transmitted image and succeeding eachother sequentially in regularlyrecurring order, means for producing anelectron beam, a screen containing substantially parallel color phosphorstrips luminescent in different colors when energized under impact ofthe electron beam, means for scanning the electron beam over scanninglines extending transversely of the strips, and means for controllingthe energization of the different color phosphor strips alongeachseparate scanning line to make their energization accord withthesequence of color representative signals in the received waves, saidmeans including control circuits, means for impressing on the controlcircuits oscillatory energy produced by scanning action of the electronbeam over the phosphor strips and connections for impressing on saidcontrol circuits control signals derived from the received waves.

10. In a color television system, image-reproducing apparatuscomprising, a multicolor kinescope having means producing an electronbeam and deliecting it horizontally and vertically to scan a raster anda luminescent screen including a multiplicity of vertical areasrespectively capable of producing light of the different component imagecolors when excited by an electron beam, said screen being additionallyprovided with correction signal-generating strips aligned andcoextensive with predetermined ones of said screen areas capable ofemitting light of a particular color and having a secondary electronemission ratio different from that of the rest of said screen, asecondary electron-collecting electrode adjacent said screen, an outputcircuit connecting said screen and said collecting electrode in which todevelop beam-correcting signals representative of the traversal of saidstrips by said beam, a reference frequency generator producing a Wavehaving a frequency equal to the color video signal repetition frequency,means coupling said output circuit and said generator to develop abeam-correcting deection voltage representative of, and in response to,phase differences between said signals and said reference frequencywave, and means responsive to said beam-correcting deection voltage tocontrol the horizontal deection of 14 said beam in a manner to eiectsubstantially accurate beam-to-screen area registration concurrentlywith the modulation of said beam by the video signal representing theimage color cor-responding to the screen area excited by the beam.

1l. In a color television system, image-reproducing Aapparatuscomprising, a multicolor kinescope having means producing an electronbeam and dellecting it horizontally and vertically to scan a raster anda luminescent screen including a multiplicity of vertical areasrespectively capable of producing light of the different component imagecolors when excited by an electro-n beam, said screen being additionallyprovided with correction signalgenerating strips aligned and coextensiverwith predetermined ones of said screen areas capable of emitting lightVof a particular color and having a secondary electron emission ratiodifferent from that of the rest of said screen, a secondaryelectron-collecting electrode adjacent said screen, an output circuitconnecting said screen and said collecting electrode in which to developbeam-correcting signals representative of the traversal of said stripsby said beam, areference frequency generator producing a lwave having afrequency equal to the color video signal repetition frequency, meanscoupling said output circuit` and said generator to develop abeam-correcting deection voltage representative of, and in response to,phase diierences between said signals and said reference frequency wave,and `means including auxiliary beam-deflection apparatus responsive tosaid beam-correcting deflection voltage tocontrol the horizontaldeflection of said beam in a manner to eiect substantially accuratebeam-to-screen area registration concurrently with the modulation ofsaid beam by the video signal representing the image color correspondingto the screen area excited by the beam.

12. In a color televsion system, image-reproducing apparatus comprising,a multicolor kinescope having means producing an electron beam anddeflecting it horizontally and vertically to scan a raster and aluminescent screen including a multiplicity of vertical areasrespectively c a.- pable of. producing light of the different componentimage colors when excited by an electron beam, said screen beingadditionally provided with correction signal-generating strips alignedand coextensive with predetermined ones of saidy screen areas capable ofemitting light of a particular color and having a secondary electronemission ratio different from that of the rest of said screen, thesecondary electron emission ratio of said luminescent screen except forsaid signal-generating strips being greater than unity, a secondaryelectron-collecting electrode adjacent said screen, an output circuitconnecting said screen and said collecting electrode in which to developbeam-correcting signals representative of the traversal of said stripsby said beam, a reference frequency generator producing -a wave having afrequency equal to the color video signal repetition frequency, meanscoupling said output circuit and said generator to develop abeam-correcting deflection Voltage representative of, and in responseto, phase differences between said signals and said reference frequencywave, and means responsive to said beam-correcting deflection Voltage tocontrol the horizontal deflection of said beam in a manner to effectsubstantially accurate beam-to-screen area registration concurrentlywith the modulation of said beam by the video signal representing theimage color corresponding to the screen area excited by the beam.

13. In a polychrome television image producer wherein a cathode-ray beamis arranged to be dellected along a series of substantially parallel andadjacent paths collectively forming repeating scanned elds and isadapted to impact a phosphor target formed from a multiplicity ofadjacent strips each of a width less than that of an image point to bereproduced, with adjacent strips formed of different compositions suchthat the group when impinged by the deected cathode-ray beam is adapted.successively to develop light in several component colors additivelyproducing White, the scanning linearizing circuits comprising means todevelop a signal pulse series indicative of the rate of repetition of asingle selected color component in the representation of an image areaconcurrently with the production of the said color image detail in thesame selected color, means to generate a local signal indicative of anoptimum rate of color repetition in the single'color, means forcomparing the two signals as to phase to develop a control signalrepresentative of the departure'from optimum, and means to accelerateand decelerate the scanning along each path under the control of thedeveloped signals.

14. In a polychrome television image producer wherein a cathode-ray beamis arranged to be deected along a series of substantially parallel andadjacent paths collectively forming repeating scanned fields yand isadapted to impact a phosphor target formed from a multiplicity ofadjacent strips each of a Width less than that of an image point to bereproduced, with adjacent strips formed of different compositions suchthat the group when impinged by the deflected cathode-ray beam isVadapted successively to develop light in the several component colorsadditively producing white, the scanning Vlinearizing circuitscomprising means to develop a. signal pulse -series indicative of therate of repeating the representation of an image area in a singleselected component color concurrently with producing light in the singleselected component color, means to-generate a local signal indicative ofan optimum rate of color repetition in the single color,

a discriminator for comparing the two signals as to phase to develop acontrol signal representative of the departure from optimum, and meansYto accelerate and decelerate the scanning along each path under thecontrol of the developed signals.

15. The polychrome television image producer claimed in claim 13,comprising, in addition, means to signalmodulate the scanning cathoderay beam so that the light developed in each component color issignal-modulated. l

16. The color television apparatus claimed in claim 13 wherein thesignals indicative of the rate of color scanning are photoelectronicallygenerated.

17. The colo-r television apparatus claimed in claim 13 comprising, inaddition, meansto produce the signals indicative of the actualscanning'rate independently of the presence and absence of signalmodulation in lthe selected color.

ReferenccsCited in the tile of this'patent UNITED STATES PATENTS2,792,523 Bendell et al. ..--f May 14, 1957 Y 5 2,877,295 Loughlin Mar.10, 1959 Bryan Aug. `11, 1959 j 18. The color television apparatusclaimed in claim 13 wherein the phosphor target comprises a series ofelongated strips-.each having one dimension less than that of thesmaller dimension of a picture point to be analyzed and the seconddimension of the order of one dimension of the raster to be traced andcomprising also means to trace the scanning beam relative to the targetso thatit traces paths transverse to the long dimension of the strips.19. Thecolor television apparatus claimed in claim 18 comprising, inaddition, scanning beam intercepting means located in proximity to thecolor strips producing one selected component color of light, and meansAfor intercepting lelectrons from the scanning cathode ray beam forgenerating the control pulses each time the said color light isgenerated under beam impact. 20. In polychrome color televisionapparatus for recreating color images upon a cathode-ray tube targetarea formed in a series of elongated phosphor-coatedstrips each ofsub-elemental width and arranged in a cyclic repeating sequence toproduce light in the several colors of the polychrome under impactexcitation by a cathode ray scanning beam arranged to be deilectedVrelative to the strips in pathsv generallyrtransverse to the longdimension, .a scanning beam control circuit comprising light-responsive`means-to develop signal pulses vindicative of the rate of beam traverseof one character light-producing phosphor, a local oscillator to developa control signal at a frequency representative of the optimum frequencyof repeating each selected color cycle, means for generating a signalindicative of the instantaneous phase vdisplacement of one of saidsignals with respect to the other,'and means for accelerating thescanning rate transverse to the strip length under the control of Vsaidgenerated Vsignal where .the said signal is ofone sign and fordecelerating the scanning rate transverse to the strip length under thecontrol of said signal where the said signal is of opposite sign,

